1. Field of the Invention
This invention relates to a photovoltaic drive motor including a photovoltaic transducer to convert light energy, i.e., electromagnetic radiation, into electrical energy to be used as a rotation motion source for rotating a rotor, the electrical energy being drived from light, including solar radiation.
2. Description of the Prior Art
A conventional photovoltaic drive motor is described hereunder.
A plurality of coils are arranged in a first circle on a surface of a disk-shaped printed circuit board. The printed circuit board is formed as a body of a insulation material. A solar cell, provided as a photovoltaic transducer, is positioned on a second surface of the printed circuit board, opposite the coils. The solar cell is electrically connected to the coils. A rotor of the motor is comprised of the printed circuit board, a shaft which is passes through a center portion of the printed circuit board, the coils and the solar cell.
The rotor is arranged in a motor case with its shaft supported by two shaft bearings. In the motor case, a permanent magnet, serving as a field magnet means, faces the coils from which it is separated by a small gap along the axeal direction of the shaft. A hole is formed in the motor case to expose the solar cell, sun rays irradiating the solar cell directly through the hole.
The solar cell, which is irradiated by the rays of the sun, converts the solar electromagnetic radiation into electrical energy. A photoelectromotive force is generated and supplied as an electric current to the coils. The coils, supplied with the electric current, generate an electromagnetic force from the coil current and interact with a magnetic field of the permanent magnet. As a result, rotor rotation is generated.
In the above-described conventional photovoltaic drive motor, the photovoltaic transducer is used only as an electrical energy supplying source to convert light energy into electrical energy. The coils are an essential portion of the structure. Consequently the structure of the rotor is complicated. Furthermore, both the coils and the photovoltaic transducer are arranged on the printed circuit board, the rotor becomes heavy. As a result, the rotor has a large inertial force, and the responce of the rotor is slow.